Device in a system operating with can-protocol and in a control and/or supervision system

ABSTRACT

A control or supervision system incorporates a digital serial communication and modules which are mutually communication communicable to this and operate with CAN-protocol. A control desk can be wirelessly connected to one or more modules operating with a signal protocol which takes no account of arbitration and/or confirmation functions appearing in the CAN-system. A particular receiving communication part executes the conversion of said signal protocol to the signal protocol of the CAN-system. A device for controlling a function in a first module in a CAN-system via a wireless connection to a second module in said system. A system of mutually separate units, whereof each unit operates with a CAN-signalling protocol, intercommunicable by means of radiocommunications operating with an identification system in which a key allocation between the units is based upon identities that are assigned by a module in the unit or a master system.

TECHNICAL FIELD

The present invention relates to a device in a machine-control systemand/or process-supervision system operating with the CAN-protocolaccording to standard ISO 11898. CAN-systems of this type comprisemodules which are intercommunicable via a digital serial communicationand in which a control and/or supervisory function can be realized froma first module or from a unit, which is communicable with theCAN-system, belonging to one or more second module(s). The presentinvention is a single-day application made together with Swedish patentapplication “Device in a control and/or supervision system” submitted bythe same applicant and the same inventor.

The present invention relates to a device in a machine-control system orprocess-control system. The said system has in the present case beenreferred to as a CAN-system, since the systems in question are requiredto use the signal protocol according to CAN (Controller Area Network,corresponding to standard ISO 11898). The invention in this case relatesto those types of CAN-system comprising modules which are connectablevia a digital serial communication and in which a function in a firstmodule is intended to be able to be observed, stimulated or registeredat a location for the placement of the first module. Reference is alsomade to Swedish patent application “Device in a system operating withCAN-protocol”, which was submitted on the same day by the same applicantand inventor.

TECHNICAL ASPECT

It is previously known to be able to control machinery and equipment atcontrol desks which are connected via fixed connections or wirelessconnections. These proposals make use of the general control andsupervision principles. With reference to control desk arrangementsproposed with CAN-protocol, the arrangements in question are primarilythose with wire connections. Reference is also made to U.S. Pat. No.5,392,454.

With machine-control and process-control systems of this category, it ispreviously known that it is necessary to supervise the aggregates servedby the 10 modules such that in fault-searching, system design, etc., itis possible to establish whether the equipment controlled by aparticular module is behaving as expected. It can be stated in thiscontext that it may be necessary to monitor the functions at valves,thermometers, etc., so that in certain functional states it can be seenor registered whether the components in question are actually performingtheir expected function. It is also known to utilise machine-controlsystems and process-control systems in which the equipment parts areconnected via relatively long digital serial communications. Theconnection can also be established at locations and sites whereaccessibility is limited.

ACCOUNT OF THE INVENTION TECHNICAL PROBLEM

In the radio-controlling of machines operating with CAN-protocol,problems arise from the fact that the protocol calls for arbitration andconfirmation functions which are extremely time-critical. In order toensure that the modules do not misinterpret a particular message inquestion, in certain cases the receipt of a one over the connection mustresult, for example, in a zero being immediately presented to preventdisturbances occurring within the system. This calls for sending andreceiving to be effected simultaneously by one and the same module,which, in turn, calls for a full duplex connection and timesynchronisation between the sending and receiving channel in each moduleand predetermined maximum wave propagation time within the system. Thisis difficult to achieve in a radio system when such a system is oftenchosen to enable the distance between the modules within a system whichare connected by radio link to be easily varied. Radiocommunication istherefore less suitable for systems using the CAN-protocol. The objectof the present invention is to solve these problems.

In certain contexts, it is vital to be able to make use of repetitionfunctions linked to machines or machinery stocks operating withCAN-protocol. At places which are difficult to survey or difficult toaccess, there is a need to build up an existing CAN-system and introducea repetition function over difficult stretches or to create on atemporary or longer term basis two separately working CAN-systemsinstead of one. In this context, there is a need to be able tofacilitate system developments and system applications. The object ofthe invention is to solve these problems also.

There is also a need to achieve effective coordination ofmachine-controls in machinery stocks, e.g. in weaving sheds in whichweaving machines have hitherto been controlled individually and providedwith their own man-machine interface such as control desks. There is awish to be able to introduce CAN-protocol into the control of machinesof this category, this having been hindered by the above-specifiedproblems. The object of the present invention is to solve these problemsalso and it is proposed, in respect of this category of machinery-stockcontrol, that the controls be effected via radiocommunication from andto a common man-machine interface, such as a control unit or controldesk. The control equipment is thereby simplified and a coordinated,effective control is able to be established in terms of service andproduction via or in the machinery stock.

Radiocommunication is often utilised between an operator's control unitand the control system of the machine which he controls. Examples ofsuch systems are radio-controlled airplanes, radio-controlledcontracting machinery, radio-controlled hoisting cranes, etc. of varioustypes. One problem is here to set up a radio channel which isexclusively between control unit and machine, such that the connectionis not disturbed by other operator/machine connections. The object ofthe present invention is to solve this problem also.

The invention also allows reduced susceptibility to theft and offershigh security within the system per se.

There is a great need to be able to carry out fault searches and testson modules which are situated at a distance apart and in which afunctional effect upon a first module is wanted to be able to befollowed at a second module, and vice versa. For instance, there is adesire in certain situations to initiate controls at a master in theCAN-system in order to obtain manifestations at one or more slavemodules. There is here a need to see whether the function is beingcorrectly performed by the components or aggregates controlled by themodule in question.

There is also a need to be able to stimulate a component or aggregate ata module and to discover what repercussions this has.

There is also a need to be able to carry out registration operations ina fault-searching and testing context for a certain period, as well asto acquire direct visual and signal information at the site for themodule subjected to testing or fault-searching.

The above must be practicable even if the modules are far apart andhidden from each other. Preferably, the above will be able to beeffected via an already existing switching function, i.e. connectionsand disconnections do not need to be made in each separate case/inrespect of each module.

The invention aims to solve the whole or parts of the above problems.

THE SOLUTION

What primarily can be considered to be characteristic of a deviceaccording to the invention is that it comprises two or morecommunication parts which form part of the CAN-system, respectivelybetween the CAN-system and the unit mentioned in the introduction, andwhich are communicable via one or more wireless connections, that when atransmission is made from a first communication part to a secondcommunication part, the parts operate with a signal protocol which takesno account of arbitration and/or confirmation function(s) found in theCAN-system. A particular receiving communication part executes orassists in the conversion of the said signal protocol to the signalprotocol of the CAN-system.

In one embodiment, the communication parts can be coupled to theCAN-system, which in the non-connected or non-activated state of thecommunication parts forms a unitary system and which in the connected oractivated state of the communication parts forms two CAN-systems whichoperate separately relative to each other.

A particular pair of communication parts can in this case operate with aprotocol which is distinct from the CAN-protocol and is better suitedfor radiocommunication, e.g. Aloha, Ethernet, the “GPSP” WaveRaiderprotocol from GEC Plessey in England, etc. In one embodiment, theinvention is utilised in respect of a machinery stock. As an example ofa machinery stock can be cited weaving machines which are installed inone or more weaving sheds and are respectively allocated one or moremodules. In this case, the unit can comprise a service unit common to anumber of weaving machines, preferably the majority or all of the totalnumber of weaving machines. This service unit can comprise or contain apersonal computer (PC).

In the case of weaving machines in a weaving shed, one or more modulesassigned to a weaving machine are connected to a service function in theweaving shed. This service function can consist of beam-changing,bobbin-changing, etc. Service staff receive information in parallel witha service machine which is appropriately connected to the particularweaving machine. Function information can therefore appear both on theunit and in control apparatus belonging to the service machine, thefunction measure or instruction in question being able to be preparedsimultaneously or in perfect coordination between the service machineand the staff involved. An effective synthesis is obtained forproduction and service measures which are necessary to the weavingmachines in order to maintain effective production. The machines can becoupled together in a control network in which a particular machine hasits own unique code and control system in order to prevent disturbancesbetween the machines. The frequencies are preferably chosen within thebroad-band range, i.e. 1 GHz or above, preferably the open ISM-band, butIR-frequencies and ultrasound frequencies can also be used. The latterparticularly in respect of acoustic communication in an underwaterenvironment.

The device according to the invention also relates to a system ofmutually separate units which are intercommunicable by means ofradiocommunications, these being able to be set up such that messagechannels can be realised between two or more of the said units. Theradio communications operate here with an identification system in whicha key allocation can be realised, which in a particular connectioninstance enables messages to be transferred between selected units only.The particular unit is further designed with a CAN-system (ControllerArea Network), in which activations, control operations, functions,stimulations, readings, etc. in modules making up the unit areintercommunicable via a digital serial connection. The latter device isprincipally characterised by the fact that in each connection instancethe key allocation between the units is based upon anidentity/identities which, during a connection process for theconnection in question, are acquired from a module in the CAN-systemconcerned and/or from a master system or master control centre. Furtherfeatures of the devices in question can be derived from the followingpatent claims.

What primarily can be considered to be characteristic of a deviceaccording to the invention, comprising the module mentioned in theintroduction, is that a radiocommunication apparatus is arranged forconnection with a part belonging to a second module in the system forthe establishment of a radiocommunication channel between the locationfor the placement of the first module and a location for the placementof the second module. At the location for the placement of the firstmodule, radiocommunication equipment can be activated for initiation viaa radio channel and the said part of the radiocommunication equipment byactivation of a signal in the second module. This signal activationcauses the first module to perform its particular control and/orsupervisory function which then becomes able to be observed orregistered in place of the first module.

In one embodiment, the CAN-system forms part of a machine-control systemand/or process-control system in which a first signal exchange accordingto the CAN-protocol obtains between involved modules within the systemfor the control operation and the performance of the process. A firstactivation of the radiocommunication equipment at the first locationhereupon gives rise to a second activation of circuits in the secondmodule. This second activation induces the said signal activation in thesecond module.

In a further embodiment, the signal activation caused by the secondactivation gives rise to message initiation in the second module, whichprepares to dispatch a message via the module's communication circuit,over the connection to the first module. The second module is hereuponable to transmit the thus generated message, with a predetermined orderof priority, in the ordinary message or signal exchange between themodules. In one embodiment, the second module can cause interruption tothe ordinary message or signal exchange in the CAN-system. That signalactivation in the second module which is herein. initiated by the secondactivation takes over the CAN-system for the generation and sending ofone or more test messages via the communication circuit and theconnection to the first module.

When its signal is activated on the basis of the second activation inthe second module, the second module can imitate a control orsupervisory function which can normally be found in the machine and/orprocess-control system. Alternatively, or as a supplement thereto, acontrol and/or supervisory function which is especially cut out for thetesting function is generated.

The radiocommunication equipment preferably operates two-way (half orfull duplex). This makes it possible for a stimulation of control orsupervisory component(s) or equipment at the first module to produce afeedback to the second module, via the connection to the second module.The latter generates a stimulation-responding information signal, whichis fed back to the radio equipment part situated at the first module.Information which is transferred via the radiocommunication equipmentcan thereby be indicated or presented on or at the saidradiocommunication equipment part at the first module.

In one embodiment, the radiocommunication equipment part at the firstmodule is connected to the control and or supervisory equipment servedby the first module and/or directly to the module.

In one embodiment, the second module is arranged such that it is merelya so-called “gateway” between the radiocommunication of the first unitand the CAN-system, i.e. a message from the first module via radio tothe second module is converted there to a CAN-message and transmitted onthe bus, and vice versa.

Further characteristics derive from the following patent claims and thedescription. The device also therefore works in cases where theequipment in the first module is stimulated, for example, manually,which stimulation can be monitored at the control orinformation-supplying unit to ascertain whether there are faults in theequipment and/or the communications.

ADVANTAGES

Radiocommunication between control units and machines in machinerystocks can be economically established even where the machines operatewith CAN-protocol. Repetition functions can be inserted into theCAN-system or the machine and/or process-control system, which meansthat connections can be established for even poorly accessiblelocations. Proven methods are in fact able to be used in connection withthe radiocommunication control operation, as regards control desks,frequency usage, security arrangements, coding, keys, etc.

The above makes it possible for testing and function-checking to beeasily carried out on CAN-modules, using simulated control operationsand stimulations which are introduced to second modules at a distancefrom the first modules. The checks can be executed even if theconnecting line is long, e.g. 800 m, or the modules are hidden from oneanother. The stimulations can also be carried out on the visuallysupervised module or its equipment/components and the reactions to suchstimulations can be obtained in a second direction within the CAN-systemand recorded at the location for the first module(s).

DESCRIPTION OF THE FIGURES

A currently proposed embodiment of a device exhibiting thecharacteristics which are indicative of the invention shall be describedbelow with simultaneous reference to the appended drawings, in which:

FIG. 1 shows radiocommunication between a unit and a CAN-system

FIG. 2 shows how a CAN-system with repetition function can be dividedinto two CAN-systems,

FIG. 3 shows how a CAN-system can be arranged with a control unit whichcan work either directly connected to the CAN-bus and then utilise powerfrom this system or via a radio channel and then be powered from achargeable battery,

FIG. 4 shows transmitting and receiving units via a radio channel in aradiocommunication system, in which transmission takes place in aprotocol distinct from the CAN-protocol and in which conversion to theCAN-protocol is realised on the receiver side, and

FIG. 5 shows a simple system in which in operator control module whichworks on the CAN-bus is easily modified from a wire-bound system to aradio-controlled system,

FIG. 6 shows a device which enables a CAN-message to be converted to aradio message, and vice versa,

FIG. 7 shows diagrammatically how protocol exchange takes place betweenthe CAN-protocol and a radio protocol,

FIG. 8 shows a radiocommunication control system in respect of amachinery stock, e.g. in the form of weaving looms in a weaving shed,

FIG. 9 shows an arrangement for weaving machines in a weaving shed, inwhich information goes out to a service car in parallel with a controlpanel,

FIG. 10 shows a simple way of setting up a secure radiocommunicationbetween a control member and a machine,

FIG. 11 shows a construction site with radio-controlled cranes and theestablishment of a radio connection between these and a particularoperator.

FIG. 12 represents a basic and block diagram of a CAN-system in whichradiocommunication equipment parts are arranged at first and secondmodules in the system and in which the radiocommunication equipment hasbeen connected to the second module in order to simulate stimulationstherein, the effect of which upon the system can be monitored at thefirst module,

FIG. 13 shows in basic representation an antenna system for longtransfer distances in respect of equipment according to FIG. 1,

FIG. 14 shows in block diagram form the structure of the module 4Aaccording to FIG. 1, and

FIG. 15 shows in diagrammatic form the framework structure for digitalsignals which are used.

DETAILED EMBODIMENT

FIG. 1 shows in basic representation a CAN-system 101A. By this is meanta machine-control and/or machine-supervision system. Alternatively, aprocess-control or process-supervision system can be obtained. TheCAN-system is represented by a number of modules 102A, 103A, 104A, whichserve their parts of the system in question. Also included are a controlunit 105A and a radio module unit 106A connectable and connected to orforming part of the module 117A. The said modules can intercommunicatevia a digital serial communication connection 107A. FIG. 1 also shows acontrol desk function 108A comprising operating levers 109A and 110A anda personal computer 111-A with possible display unit 112A. The unit 108Afurther comprises a module 113A, which can be synthesised with themodules on the bus via a radiocommunication system comprising a part114A, and possibly also an adjustment unit 118A, in the unit 108A andthe said radio module 106A. The radio module 106A and the part 114A cancomprise transmitter and receiver, so that a two-way communication 115A,116A is obtained. Communication takes place via established radiochannels in the radiocommunication equipment and the latter operatespreferably in the broad-band range, see above. The units 116A and 114Aare provided with antennae 106 aA and 114 aA for the said communicationfacility. The modules 102A, 103A, 104A can in this case representmodules forming part of machines in a machinery stock in which aparticular machine can operate with a number of modules. There istherefore a possibility of accomplishing controls from the unit 108A ofthe modules in question via the CAN-system. The said machines in thesaid machinery stock can consist of weaving machines—described ingreater detail below—installed in a weaving shed or of hoisting craneswithin a construction area.

FIG. 2 shows how a CAN-system 201A having a repetition function can bearranged to form two different CAN-systems 202A and 203A, the respectiveCAN-system here being equipped with radio modules, which can comprisetransmitter and receiver in accordance with the equipment 106A, 117Aaccording to FIG. 1. The radio modules have been given the designation204A and 205A respectively. The first CAN-system has the modules 206A,207A, 208A, 209A and the second CAN-system has the modules 210A, 211A,212A. Control functions can be performed via the modules 210A, 211A and212A, via the pilot pins 213A, 214A and a personal computer 215A. It theradio modules 204A and 205A are uncoupled, then the CAN-buses 216A and217A of the sub-systems can be joined together to form a common CAN-bus218A in which the junction point has been denoted by A. In the case ofseparate coupling and jump coupling, the CAN-bus ends would naturallyhave to be correctly terminated and a power supply suitably arranged.Except for certain accruing delays to the message, the divided systemwill function as if it were coupled together without any changes in thesystem's software.

FIG. 3 shows a further variant of a CAN-system 301A with modules 302A,303A, 304A and 305A. Here too, radio modules 306A and 307A are utilised.The radio module 306A is tied to the CAN-system 301A, whilst the radiomodule 307A is assignable to a further CAN-system 308A, which can beconnected in two alternative ways to the CAN-system 301. The one way isrealized via a mechanical, galvanically separated or wireless connection309A or via the radio modules 306A and 307A, which operate in a mannercorresponding to the radio modules according to FIGS. 1 and 2. TheCAN-system 308A is provided with three modules 310A, 311A and 312A forthe inputting and receipt of information which is relevant to the systemin connection with control and/or supervision within the system. In thiscase, a battery system 313A is utilised to power the CAN-system 308A.When the system 308A is used at a distance from the system 301A and theradio connection is utilised, then power is supplied from the batterysystem 313A. When the systems are coupled together, then the batterysystem 313A is connected directly up to the power unit 315A of theCAN-system 301A via the inductive connection 314A and the battery systemis then able to charge its integral accumulators. The CAN-system 301A iscoupled together with 308A by the connection 315A via an inductivecoupling 316A. A system can thereby be coupled together or separatelycoupled to form two sub-systems without mechanical connectors havingpins and sockets, which often cause problems when exposed to wear andtear, corrosion and physical damage. In many cases, one and the samecontrol unit can operate either conventionally ufixedw mounted andconnected to the CAN-network or as a remote control unit. In the fixedposition the batteries are loaded. Whenever the unit is then wanted tobe used as a remote control unit, it is simply disconnected from thesystem. In the fixed-coupled position, the radio units have agreed onall parameters which are required for wireless communication. Anadvantage is also that the operating unit is able to be removed from thecontrolled unit and without a control unit the machine is difficult tosteal.

FIG. 4 shows a monitoring/control unit 401A, having one or more CPU's402A, memories 403A, a CPU-integrated or free-standing CAN-Controller404A (for example Intel 527A), a CAN-driver 405A (for example Philips251A), communication adjustment circuits 406A, etc., diagrammaticallyillustrated, built for the CAN-protocol, which are connectable to aradio unit 408A and also connectable to a CAN-connection 407A. The radiounit 408A comprises two communication parts, a radiocommunication part409A having hardware and software, which enables a wirelesscommunication to be set up between different radio units, and a parthaving hardware and software, incorporating one or more CPU's 410A,memories 411A, communication adjustment circuits 421A, etc.,diagrammatically illustrated, which allows communication with the unit401A. Examples of such radio units are WaveRider from GEC (GB) andexamples of a CAN-unit are CANnonBall and mini-CB from XVASER AB (SE).The radio part 408A and the CAN-part 401A have at least one CPU each andcan intercommunicate via a serial or parallel interface 413A. The parts401A and 408A can be built together in a common casing 414A or each inits own casing, indicated by 415A, and can be connected by a connector416A. An advantage of having the radio unit 408A and the CAN-unit 401Amounted each in its own casing is that the radio unit can be easilyexchanged in the event of a fault, replaced by a similar radio unit inorder to satisfy national or regional radiocommunication regulations, orcan alternatively operate with some other wireless communication based,for example, upon infra-red or visible light, ultrasound, etc. TheCAN-part can in this case be a standard unit with a parallel or serialoutput which allows connection to a unit equivalent to 408A. Each radiopart has a unique identity, in the case of WaveRider an Ethernetaddress, and each CAN-unit has a unique identity, for example anEAN-number including a serial number. Each unit which will be able to becontrolled also has a unique identity, for example an EAN-numberincluding a serial number.

The radio unit operates independently as regards radiocommunication andhas a network protocol for this. All radio units can intercommunicatewithin radio range on a common channel. Two or more radio units can beallocated or can themselves set up a channel which is exclusive to them.If further differentiation of the radio traffic is required, then two ormore radio units can establish an exclusive message channel within achannel by the messages being encoded with their own common key. Eachstation can be allocated a station name constituted, for example, by abinary code or an ASCII-file. By having two separate identificationsystems, one for radiocommunication and one for CAN-communication, avery secure and flexile communication system can be established in whichthe system, apart from being a communication system, can also be used todistribute and check the authority of operators to operate machines.

U.S. Pat. No. 5,392,454 describes how two radio units can set up acommon exclusive communication channel by first seeking contact witheach other via another type of communication channel and by thereexchanging information about each other's unique identity. By markingits messages with its identity during ordinary communication, aparticular unit can thus filter out those messages which are intendedfor the unit in question. The fact that the identification of themessage is based upon the identity of the radio unit represents a majordrawback, firstly in respect of the exchange of radio units and secondlyif multicast-type connections are wanted to be set up. The consequenceof the solution proposed in U.S. Pat. No. 5,392,454 is that the radioconnection is tied between the transmitting and receiving radio unit andnot between operator unit and machine or between machine sub-system andmachine sub-system. The radio communication system can be regarded asthe master machine-control system. The radiocommunication units areregarded as special units within the system.

In CAN-systems, for example those operating with CAN HLP (Higher LayerProtocol) “CAN Kingdom”, it is usual firstly for each node or module inthe system to have its own unique identity, which is based, for example,on an EAN-number and a serial number, and secondly for there to be amodule or node constituting a system node in the machine system. Theidentity of this node can also be used as identity for the machine. Inthe present invention, the radiocommunication unit is regarded as aCAN-node of whichever type, equating, for example, to a valve unit or ajoystick unit. The radiocommunication system is thus regarded as thesubordinate machine-control system. When the system is started up or assoon as a radio unit is connected to the system, the system node candetect this, for example by a method described in CAN Kingdom. Dependingupon the situation, the system node can assign to the radio unit ageneral public network key or a unique key. A simple way of constructinga unique key is to base this upon the identity of some node incorporatedin the system, since all of them have a unique identity, inclusive ofthe system node itself. If, for some reason, a node other than theidentity of the system node is chosen as basis for the exclusive networkkey, then this is entirely possible, at least in systems based upon CANKingdom, with maintained system security, since the system node is awareof all integral nodes and no node can be exchanged and work within thesystem without the consent of the system node. From a securityviewpoint, it is vital that it is the system node of that sub-systemwhich is critical to security within the total system which determinesthe network key and possibly also provides a jump plan or alternativelya dispersion code, depending upon whether a jumping frequency or spreadspectrum technique has been chosen. Examples of a suitable radioemploying the latter technique is the “2.45 Spread Spectrum Transceiver”from CRL Instrumentation in England. For example, in a system comprisinga hoisting crane and a remote control unit, it is the system node in thehoisting crane which has to assign the common network key to aparticular radio unit, not any of the radio units or the system node inthe remote control unit. Alternatively, network keys can be distributedat a still higher level within the system. For example, a unit which iscommon to a construction area can distribute network keys via a commonchannel to remote control units and cranes. The area-common unit thenhas complete information on all cranes and the identities of remotecontrol units within the area. It is vital that the radiocommunicationunits should be at a low level systematically within the machine systemand hence fully exchangeable without security risk. The problemsassociated with radio transmission, such as, for example, jump plan,jumping frequency, dispersion code, identification of radio transmitterand receiver, distribution of station identities, etc. can be solvedwholly within the radio system range and the machine system constructorneeds only to ensure an adequate network key distribution. Ahierarchically structured machine system includes an organisation forthe generation and distribution of network keys and an organised way ofidentifying individual modules and groups of modules. The radio systemincludes an organisation for the generation and distribution ofcommunication channels and an organized identification of individualsand also possibly groups of radio stations. The fact that the machinesystem distributes the network keys and has scope to acquire and employinformation on the identities of stations forming part of the radiosystem means that radiocommunication in a CAN-system can be usedsecurely. The identity of the station in the radio network can beexchanged by the system node for the identity of the system node, inwhich case the system ceases to form part of the original radio network.

Having CAN-modules whose only tasks are to constitute units for wirelesscommunication, hereinafter referred to as WCANM, is a major advantage inCAN-systems. An example: We have two wireless units, WCANM1 and WCANM2.In stage one we couple them together via the CAN-connection and theyperform the start-up process and can subsequently intercommunicate in asecure manner. In a system which is traditionally constructed, then itis now possible to remove a unit, for example a control lever andmonitoring unit, and replace this with a WCANM1. The removed module isnow coupled together with WCANM2 and we have a wireless connectionbetween the monitoring/control unit and the rest of the system. In itssimplest form, WCANM1 will now receive all messages on the CAN-bus. Asand when a message is correctly received, it is repackaged into aWCANN-message [sic] and sent to WCANM2, which unpacks the message andconverts it into a CAN-message and sends it to the monitoring/controlmodule. This module cannot distinguish between a message which hasundergone these conversions and a message which has arrived directly onthe CAN-bus, if the CAN-Identifier is the same. When thecontrol/monitoring module sends a message, the reverse takes place.WCANM2 receives the message, repackages it, transmits it to WCANM1,which repackages and sends out the message on the CAN-bus.

FIG. 5 illustrates a process according to the above. A CAN-systemcomprises a CAN-bus 500A, to which the modules 501A, 502A, 503A, 504Aand 505A are connected. The module 505A is a control module to which thecontrol levers 508A and 509A are connected and with which the controlcommand can be given to 501A and 502A or 503A and 504A respectively. Bydecoupling the module 505A from the CAN-bus 500A and instead connectingup the radio module 511A and connecting the radio module 510A to theCAN-bus instead of the module 505A, a wireless connection has beenobtained between the control module and the CAN-bus.

Below and in FIG. 6, a detailed account is given of how a CAN-message isconverted into a radio message and vice versa. A message is created bythe CPU 602 in module 601A and transferred to its CAN-Controller 603Afor dispatch. Apart from data, the CPU sends information on theCAN-Identifier to which the data is to be coupled, on whether thisidentifier is of the standard or extended type, on the fact that it is adata message and not a so-called “remote request” and on the number ofbytes which the data occupy in the data field. The CAN-Controllerconverts this information into a bit pattern according to theCAN-protocol, in which, inter alia, a CRC check code for the message isworked out, and transmits the bit pattern 701A on the CAN-bus 600Aaccording to the rules of the CAN-protocol via the CAN-driver 604A. Oncethe CAN-Controller 607A of the WCANM-module 606A has correctly receivedthe message, then information corresponding to the CPU in module 601A isdownloaded to its CAN-Controller so as to be accessible to the CPU 608Aof the WCANM-module. This reads the received information and packages itinto a data format which is common to WCANM-modules:

Bytes 0-3 CAN-Identifier Byte 4 Data Length Code Bytes 5-12 Data Field20

Note here that a CAN-Identifier is only a bit pattern and that thearbitration characteristic associated with this part of a messageaccording to the CAN-protocol is of no importance to the radiotransmission and that the CRC-code and acknowledgement bit are nottransferred. The data string 702A, in FIG. 7, according to the above istransmitted to the CPU 610A of the radio unit 609A via a local serial orparallel bus 611A for sending. (The interface 611 can comprise eightleads for data, six leads for handshaking, three in each direction, anda feedback signal lead for initiating the radio at the start-up of thesystem). The CPU 610A then deposits the data string as data according tothe protocol used by the radio units amongst themselves 703A. Here thedata are treated as whichever data and the CPU 610A is not thereforerequired to have any information on the CAN-protocol. The radio messagehaving been transmitted, the CPU in the radio unit of a receivingWCANM-module, following receipt according to the radio protocol, usesthe local bus to transmit the received data string 704A to the CPU ofits module's CAN-part. The CPU of the CAN-part then creates aCAN-message 705A in accordance with the format of the data string andpresents this to its CAN-Controller for dispatch on the CAN-bus and theprocess continues in the customary CAN manner. The CAN-Controllercalculates a new CRC check code and presents a one in theacknowledgement slot, since it is transmitter of a message which is newto this part of the system.

In CAN-systems constructed with CAN Higher Layer Protocol “CAN Kingdom”,an application in a module is tied together with a CAN-Identifier via aso-called “Folder” to allow the data exchange between applications indifferent modules to be coupled together. If the CAN-system isconstructed according to CAN Kingdom, the

Folder number can be used instead of the CAN-Identifier in the format ofthe data string 702A and the Data Length Code omitted:

Byte 0 Folder Number Byte 1-n Data n = 0 . . . 8

Other necessary information derives from the particular “Folder Label”in accordance with the CAN Kingdom protocol. The length of theether-borne message is thereby reduced. Furthermore, differentCAN-Identifiers can be used for the very same message in the varioussub-systems. This can be an advantage, since the priority of the messagecan then be adjusted to the conditions in the particular sub-system. Insystems developed for radiocommunication, only messages necessary to aparticular receiver are sent via radio and each sub-system has aninternal flow of messages between its nodes.

In CAN-systems it often happens that modules are set to receive onlycertain messages. This is generally done by filtering out certain bitpatterns in the arbitration field of the CAN-protocol, which inspecification ISO 11898 is known as the Identifier Field. Since, from aCAN viewpoint, WCANM-modules can be quite ordinary CAN-modules, thesealso have the scope to filter out messages on the bus. If it is knownwhich messages are to be received on both sides of the wirelesscommunication, then WCANM1 and WCANM2 respectively can be set to filterout those messages which are to be received on the respective other sideand thereby reduce the load on the wireless connection. Since there isno known method of satisfying the time demands which are placed upon theacknowledgement bit of the CAN-protocol via a wireless connection with ahigh bit speed, typically 125 kb/s to 1 Mb/s, over longer distances,typically from a few meters up to five hundred meters, the wirelesscommunication is not bit-synchronous with the line-bound communication.Since the CAN-protocol is not followed in ether transmission, this canoften be done faster and with different scheduling of the messagetransmissions. If standard circuits for CAN are used, then it may beexpedient to take the message as it appears in the normal receptionbuffer which is read by the CPU, i.e. with CAN ID field, control fieldand data field, but without start bit, stuff bits, CRC bits, etc., andto transmit this according to a protocol suitable for wirelesscommunication. Another alternative is to receive from the CAN-bus entirebit streams and to buffer these as far as the acknowledgement bit. Whenthis is read to zero on the CAN-bus, the packet is transmitted via theether and, following receipt, the bit stream is transmitted on theCAN-bus on the reception side. From the acknowledgement bit onwards, thereceiving WCANM-module itself creates remaining bits according to theCAN-protocol. If, during this period, the first WCANM-module reads anerror frame after the acknowledgement bit during the remaining part ofthe CAN-message, then an error code is immediately transmitted to thereceiving WCANM-module, which then sends out an error frame on itsCAN-bus. This is an effective way of sending CAN-messages, since CAN'serror controls are utilized (and therefore no error control is requiredin the ether protocol) and there are few bits needing to be transmitted.The problem remains however, when some bit is incorrectly received fromthe ether or, worse still, a CAN-error arises on the CAN-bus belongingto the receiving side. It can then be too late for the receivingWCANM-module to send an error message over the ether. The originalmessage can already have been accepted on the sending side. This problemcan be solved in the CAN Higher Layer Protocol.

A further way of compressing the message which can be utilised,especially when the ether communication is operating at high bit speed,is for the bits of the CAN-message on the sending side to be received upto the point where the CRC-code and the stuff bits are removed, sincethese are not involved in the working-out of the CRC-code by the CANerror protocol. This packet is transmitted via the ether and, if theCRC-code is correct on arrival, then a CAN-bus is recreated.

The communication between WOANM-modules [sic] can be of the full duplexor half duplex type. Full duplex offers the fastest transfer, since, ifthe receiver detects an error, it can immediately send back an errormessage to the transmitter. In the case of half duplex, the receiverwould have to wait until the whole message is sent before a reply can begiven. Radio networks are most commonly of the half duplex type. Atypical sequence is as follows:

Transmitter Receiver 1. Set up connection. 2. Acknowledgement 3. Sendsmessage 4. Acknowledgement 5. Disconnect the connection

A more effective procedure is to send short messages constantly to andfro between the transceivers. A CAN-message is always short incomparison to necessary information in a radio network protocol for the2.4 GHz band (the ISM band), in the order of magnitude of 11 to 154 bitsdepending upon the way in which the information is packed in the radioprotocol. It is therefore expedient for the CAN-information to beincluded in the “Establishment of connection” message and theacknowledgement message, thereby providing an effective use of thechannel. The fact that a short message is “ping-ponged” in this waymeans that a system-supervising node in the CAN-system has the chance tohave continuous information stating that the radio connection is intactand functioning. A broad-band communication further requires that theclock in a particular transceiver module shall in some way besynchronised with a real or virtual system clock. A constant exchange ofshort messages between stations in the system allows good precision tobe maintained in the system's clocks, thereby enabling the creation ofan effective broad-band protocol built on jumping frequency orbit-pattern synthesis and enabling the clock of the radio system also tobe used as a system clock within the CAN-system.

An ever increasing number of modern weaving looms are constructed with aCAN-system. Each weaving loom has a display, a key set and very oftenalso a memory card reader. These devices are utilised only when a personoperates them, i.e. for the vast majority of the time they are totallyredundant items of equipment. It is usual for one person to haveresponsibility for twenty or so weaving machines. Often all weavingmachines are connected to a network having a supervisory function andthe person in charge acquires information telling him which machine togo to in order to carry out some form of service. By connectingWCANM-modules to each weaving machine and a WCANM-module to a portableunit suitable for passing and taking information from a person, aso-called “Man Machine Interface (MMI), for example a portable personalcomputer, a number of advantages are attained. All displays, key setsand memory card readers can be removed. When the person stands at themachine, he connects his MMI to the CAN-network in the manner previouslydescribed. Since only one MMI is required per person, this can beconsiderably more powerfully designed than if there were one to eachmachine. Data files which were previously transferred using memory cardscan now be transmitted from the MMI. Fault analysis programs, graphicpresentation, tuning tool programs, etc. can be incorporated in the MMIand keyboards, mouse, etc. can be made user-friendly and upgraded moreregularly than the machines. Communication with the person often drawson greater computer resources than the machine-control function, so thatthe machine-control function can be made cheaper, more secure and moreeffective in that these functions are taken over by the MMI.

When the operator is not directly connected to a machine, he isconnected to the wireless network. As soon as a machine requires actionon the part of the operator, the machine sends out a message on thewireless network. The operator brings up on his display a list of allweaving machines which have requested assistance and for what reason. Ifmore than one machine has requested assistance, the operator can choosethe order in which he shall attend to the machines and he is alsoprepared for what has to be done so that he has suitable tools with him.

FIG. 8 shows a diagrammatic representation of a device according to theabove. Each weaving machine 808A, 802A, 803A, 804A, 805A, 806A and 807Ais equipped with radio modules 801 aA, 802 aA, etc. and has in each casean internal CAN-control system which can communicate with the radiomodule. The operator has a PC 808A to which a radio unit 808 aA isconnected. When the operator is supervising the plant, all radio unitsoperate on the same channel and information can be exchanged between thePC and all weaving machines. When the operator is working on a weavingmachine, the PC and the weaving machine use an exclusive channel, directcommunication with the weaving machine 801A being illustrated in thefigure. A further advantage is that the wireless network can replace thecurrently wire-bound network for production data to and from themachines and for supervision thereof.

The automation of a factory often incorporates various types ofdriverless trucks and similar equipment which also have an internalCAN-control system. These can also be connected up to the wirelesssystem. FIG. 9 shows a diagrammatic representation of a small part ofsuch a system with a weaving machine 902A, a driverless truck carrying areplacement beam 904A and an operator unit 903A. If, for example, a warpbeam is to be replaced, then a message 901A reporting this can pass fromthe weaving machine 902A both to the operator 903A and to the unit 904Atransporting replacement beams. This, in turn, can send a message 905Ato the operator about its status. When the operator arrives at themachine, the driverless truck with the replacement beam is alreadythere. In the event of further automatisation, the fixed machineinteracts automatically with the moving machine and the operator issummoned only if the machines, for some reason, have failed in theirtask.

FIGS. 10a and 10 b show an example of the above process. Amonitoring/control unit 1001A equipped with a radio unit 1011R isconnected via a CAN-bus 1002A to a machine 1003A equipped with a radiounit 1003R. The system-supervising node 1004A of the machine detectsthat a monitoring/control unit 1001A is connected to the machine andasks the system node 1005A of the unit 1001A for the EAN and serialnumbers of the monitoring/control unit and uses these to check whetherthe unit 1001A is of the right type and whether the individual isauthorised to control the machine 1003A. The method for carrying outsuch a check is, inter alia, described in CAN Higher Layer Protocol “CANKingdom” . If another monitoring/control unit 1006A already has controlover the machine, the connected unit 1001A is denied furthercommunication with the system in the machine 1003A. If no previousmonitoring/control unit has control and type and possibly also the newindividual is authorised to control the machine, then the machinetransmits a unique station name 1007A, for example the EAN-number,inclusive of serial number, of the unit 1001A. This station name issubsequently used jointly by the machine and the monitoring/control unitas identity for their communication channel. The CAN-connection 1002A isdisconnected and communication can be made via radio as shown in FIG.10b. FIG. 10b has revealed that the radio units 1001R and 1003R havebeen exchanged for the compatible units 1011R and 1010R aftercommunication has been established. This is totally feasible by virtueof the fact that a particular system node 1005A and 1004A delivers theagreed channel code to the respective new radio units, once these havebeen connected to the respective CAN-network.

FIG. 11 shows a more complex process. A company has a number of cranes1101A, 1102A, 1103A at a work site. All cranes have a unique identity, 1i, 2 i, 3 i and are each equipped with a radio unit 1 r, 2 r, 3 r. Eachcrane operator 1104A, 1105A, 1106A has his own monitoring/control unitwith radio. Each such monitoring/control unit has a unique identity, 4i, 5 i and 6 i respectively. Whenever a crane does not have activeconnection with a control unit, it listens in on a channel 1107A whichis common to the work site. Whenever a crane, in this instance the crane1102A, is assigned to a crane operator, in this instance 1106A, acentral radio unit 1108A seeks contact with the assigned crane 1102A,which is identified by 2 i, and informs the crane operator 1106A of theidentity of the monitoring/control unit, 6 i or alternatively thenetwork key based on 6 i. Once the crane operator is on the spot, hestarts up his monitoring/control unit. The crane unit seeks contact onthe general channel with the selected monitoring/control unit 1006Ahaving the identity 6 i and when they have made contact with each otherthe crane reports its identity 2 i and the fact that it is master of theconnection. A connection is then set up on an exclusive channel 1109A,i.e. the crane communicates how frequency jumping is to be done. Inbrief, it is therefore the case that cranes which do not have contactwith a selected control unit, in terms of radiocommunication, complywith the jumping frequency from a central unit. Once contact is obtainedwith a selected monitoring/control unit, the crane establishes contactwith this, leaves the central unit and assumes control over thegeneration of frequency jumping. The monitoring/control unit complieswith this. If the radio connection is of the “spread spectrum” type,then the dispersion code is given instead of the jump plan.

A plurality of control units can be assigned to one and the same crane.They then belong to the same network. In the working range of the crane,a particular monitoring/control unit is assigned to a part-region. Thepart-regions can be partially overlapping or the crane can follow apredetermined path between the part-regions. The crane is thereby ableto be reliably controlled at a number of sites. When the load entersinto a part-region, it obeys only that control unit which is responsiblefor the area. There are a number of ways of solving the allocation ofwho has control over the machine on a given occasion. A furtheralternative is that the machine, after a certain period in which nocontrol command is forthcoming, for example two seconds, accepts thatparticular transmitter, of those which are accepted, which first issuesthe control command. The machine then obeys this transmitter until suchtime as it has failed to give any control commands for a two secondperiod.

In systems, especially those which are constructed according to theprinciples contained in CAN Kingdom, in which a plurality of remotecontrol units are able to operate one and the same unit, controlcommands from a particular remote control are assigned to aCAN-Identifier by the system node of the controlled unit. The controlcommands are in this case first received by the system node, which, inturn, transmits control messages on the CAN-bus of the machine. Thesystem node can receive control commands from all remote control unitswhich communicate on the network key common to the machine and can thenselect which remote control unit's control commands will be implementedaccording to a set of rules, for example the work area within which theunit is situated or, quite simply, that the remote control unit whichfirst gives a shift command then retains control until it issues a codefor relinquishment of the control, is shut off or remains inactive for apredetermined period. Thereafter, the system node of the machine waitsfor a first best command from any of the authorised remote control unitsand then executes control commands only from this latter until theparticular remote control unit hands over control according to theabove.

In a number of machines, for example process machines, a large number ofmeasuring points and adjusting appliances are apparent, which aregeographically dispersed and on many occasions poorly accessible. Theoperator sits in a room in which he supervises and controls the entiresystem via VDU's. Whenever something is detected which calls foron-the-spot observation, a communication problem arises. For example, aclosed position of a valve is indicated, which should be open. When theoperator makes an on-the-spot visual inspection, he sees that the valveis open. Has it opened whilst he was on his way to the valve or is thevalve signalling a closed position despite the fact that it is open? Ifnow a WCMNM-module [sic] is connected and the has a MMI as previouslydescribed, then he can read on the spot the message which the valve istransmitting on the CAN-bus and decide whether there is a fault with thevalve or not. The WCANM-module connected to the CAN-bus, from theviewpoint of the CAN-signal, can be in a totally passive mode, i.e. nottransmitting a single bit, not even an acknowledgement bit. It can alsohave a CAN-active mode, so that the operator from his MM is able tocommand the valve to open or close so as to monitor its functioningthere on the spot. Of course, the control system for the process plantwould have to be made such that the operator's actions do not jeopardisethe security of the process.

FIG. 12 illustrates a machine-control and/or process-control system withits modules 1A, 2A, 3A and 4A, which are intercommunicable via a serialdigital connection 5A in a manner which is known per se. In order tosimplify representation, the designation “CAN-system” is applied to thissystem. According to the invention, the module serves aggregates formingpart of the said machine-control system and/or process-control system.In FIG. 12 a valve in the aggregate is indicated by 6A and a thermometerin the aggregate by 7A. The length L of the connection 5A can berelatively long and can stretch over 200 m, for example. The modules andaggregates in the system can also be situated out of sight of eachother.

In systems of this category, there is a need to be able to initiate afault-searching, testing, control operation, etc. at the first module1A. Such fault-searching or equivalent can require that second modulesin the system need to be stimulated or need to establish signaltransmissions or signal receptions at certain stages of the fault-searchor equivalent. In order to save staff, a radiocommunication apparatus isused, comprising two radiocommunication equipment parts 8A and 9A. Thefirst part 8A can be independent from the CAN-system, whilst thecommunication part 9A is connected to or forms part of the secondmodule. The connection between the part 9A and the module 4A can hereinbe made via a connection 10A, which can consist of a physicalconnection, non-galvanic connection, wireless connection, etc. Themodule 4A can be temporarily or permanently connected to the CAN-bus.The radiocommunication equipment 8A, 9A operates, where appropriate,with two-way connections 11A, 12A. The communication equipment 8A, 9Acan in this case utilise one or more channels, with use preferably beingmade of radio channels in the broad-band range, i.e. in the range offrequencies above 1 GHz, for example the ISM-band. Theradiocommunication equipment part 8A is provided with a control panel13A, which can be of a type which is known per se. The panel isconnected to the transmitting and receiving unit 14A of the part 8A,which incidentally can be of identical type to 9A, via an adjusting unit15A. As a supplement thereto, the panel can be directly connected to theaggregate or components served by the first module 1A. This connectionis effected via a second adjustment unit 16A and the connection per seis symbolised by 17A.

An initiation il at the panel 13A induces an activation of thetransmitting part 14A, which, via a channel 11A, transmits theactivation to the radio receiver part 9A. This receipt gives rise to asignal generation i2 to the module 4A via an adjustment unit 23A. Themodule contains a microprocessor 18A, which causes a signal message 19Ato be generated, which is then transmitted to the connection 5A via thecommunication circuit 20A of the module 4A (see FIG. 1). Thetransmission can be made according to an order of priority which isdetermined by the CAN-protocol and in which the module, after admissionto the connection 5A, is able to transmit the message in question to thefirst module. Once the message 19A is received in the first module, afunctional stimulation of the component 6A, 7A or the equipment inquestion is realised, which functional stimulation is provoked by theinitiation i1 at the control panel. The control operation can in thiscase comprise a reversal of the valve 6A, a raising or lowering of thetemperature 7A, etc. The said reversal or temperature change can bevisible to an observer at the first module. Through stimulations of hiscontrol unit 13A, the observer is therefore able to obtain visualevidence of whether the control system in question is accomplishing whatit is meant to. At the control unit 13A, information 13A can also beobtained from the components or aggregate served by the module 1A. Bykeeping the radiocommunication equipment connected, registration andviewing can be carried out for shorter or longer periods of time.

Alternatively, a manual, electrical or other stimulation of thecomponents or of the aggregate served by the first module 1A caninitiate a message 21A generated in the first module, which message istransmitted to the second module 4A via the communication circuit 22A inthe first module and the connection 5A. The said signal message 21Ainduces a signal initiation i4 in the second module and activation ofthe transmitter part in the radiocommunication equipment part 9A. Via achannel 12A, the information in question is transmitted to the receivingpart in the radiocommunication part 14A and thereupon gives rise to thegeneration of an information signal is to the adjustment unit 15A, foronward conveyance to the control unit 13A or an information-supplyingunit at which the information is displayed or registered. A location orsite for the first module 1A is indicated by A, whilst a correspondinglocation or site for the module 4A is indicated by B. After the operatorhas carried out a check or fault-search at module IA, he can proceed tomodule 3A, for example, and carry out equivalent work, providing thatthe module 4A is kept connected. He does not in this case need toconnect any equipment to the CAN-bus, but can continue to use theradiocommunication equipment 9A to transmit suitable messages andreceive chosen messages on the CAN-bus, via the still connected units 4Aand 9A. For communication over very long distances, up to a fewkilometers, it may be necessary to have directional receiving antennaein order to satisfy standards relating to maximum transmitted power.FIG. 13 shows such an arrangement for radiocommunication units ofpreviously described type, 24A and 25A, which are each equipped with anomnidirectional transmitter antenna 24 aA and 25 aA respectively and adirectional antenna 24 bA and 25 b respectively. Other equipment in FIG.1 in symbolised by 4A′ and 8A′.

FIG. 14 shows a diagrammatic representation of a monitoring/control unit201A (cf. 4 in FIG. 1), having one or more CPU's 202A, memories 203A, aCPU-integrated or free-standing CAN-Controller 204A, a CAN-driver 205A,communication adjustment circuits 206A, etc. The unit 201A is built forthe CAN-protocol and is connectable firstly to a radio unit 208A andsecondly to a CAN-connection 207A. The radio unit 208A comprises twodiagrammatically illustrated communication parts, a radiocommunicationpart 209A having first hardware and software, which enables a wirelesscommunication to be set up between different radio units, and a secondpart having hard and software,, incorporating one or more CPU's 210A,memories 211A, communication adjustment circuits 212A, etc., whichallows communication with the unit 201A. Examples of such radio unitsare WaveRider from GEC Plessey (GB) and examples of a CAN-unit areCANnonBall and mini-CB from KVASER AB (SE). The present invention can beimplemented using these standard units. The radio part 208A and theCAN-part 201A have at least one CPU each and can intercommunicate via aserial or parallel interface 213A. The parts 201A and 208A can be builttogether in a common casing or, as in FIG. 5, can be applied each in itsown casing 214A and 215A, and can be mutually connected by a connector216A. An advantage of having the radio unit 208A and the CAN-unit 201Amounted each in its own casing is that the radio unit can be easilyexchanged in the event of fault and replaced by a similar radio unit inorder to satisfy national or regional radiocommunication regulations.The CAN-part can in this case be a standard unit with a parallel orserial output which allows connection to a unit equivalent to 208A. IfWaveRider is chosen as the radio part, the interface 213A will consistof eight lines for data, a so-called “data bus”, six lines forhandshaking (three in each direction) and one line for a feedback signalfor initiating the radio when the system is started-up. Each radio parthas a unique identity, in the case of WaveRider an Ethernet address, andeach CAN-unit has a unique identity, for example an EAN-number includinga serial number. Each unit which will be able to be controlled also hasa unique identity, for example an EAN-number including a serial number.

Data transfer of an eight-bit byte from the CPU 202A to the CPU 210A iseffected such that 202A activates an interruption signal to 210A, whichresponds with an acknowledgement signal indicating that it is ready toreceive data. (Otherwise a signal is activated which signifies “tryagain once more” ). 202A presents a byte on the data bus and activatesthe signal “data are accessible” . 210A reads the byte, acknowledges thetransfer and stores it away in the memory 211A. This is repeated untilall of the byte is transferred. Transfer from 210A to 202A is carriedout in reverse.

FIG. 15 describes a detailed illustrative embodiment of signalling froma module corresponding to the panel 13A according to FIG. 1, generationof a message and the shaping of the message and its insertion on the busand reception [lacuna] a module corresponding to 1A. FIG. 15 shows onlyan operator unit 301A connected to a communication unit 302A via aCAN-interface 303A and a communication unit 304A and a valve withcontrol electronics 305A connected to a CAN-bus 306A. Other modulesconnected to 306A are not depicted, but the total system corresponds tothat shown in FIG. 1. Both the units 302A and 304A each constitute acomplete radio unit corresponding to the whole of the device in FIG. 2,i.e. the radio unit can send and receive a message both via a CAN-busand via the ether. A modulation command to the valve 305A (cf. 6 inFIG. 1) is generated from the operator unit 301A and is transferred as aCAN-message 307A to the CAN-Controller of the communication unit, whichforwards the data 308A to the CPU in the CAN-part. This creates amessage 309A formatted for the radio part. 309A is described in detailby 310A, which has the following byte sequence: an overhead block withthe parts 321A and 322A, in which 321A comprises two bytes 311A whichindicate the number of bytes making up the message inclusive of 311A, atwo-byte sequential number 312A (for suppression of subsequent multiplytransmitted radio messages) and a six-byte long destination address313A, a six-byte long consignor address 314A, two bytes 315A indicatingthe number of bytes of user data 316A to follow, and the part 322A madeup of two or three bytes 317A which conclude the string. The user data316A are the same as 308A. The CPU in the radio part takes charge of thearrived string and converts it into a radio message 318A with anecessary overhead 319A—for setting up and synchronising the radiotransfer—and 320A for concluding the sequence and ensuring it wascorrect in terms of the CRC check total, etc. The radio overheadincorporates the information 321A and 322A. The radio module in thecommunication unit 304A receives the string 318A and recreates thestring 310A, this being transferred to the CPU of the CAN-unit, whichextracts 323A and creates the information for the CAN-Controller, whichthen, in turn, presents the CAN-message 324A on the CAN-connection 306A.The valve unit 305A now receives the command via the CAN-connection andimplements the same, which can be verified by the operator.

The invention is not limited to the embodiment shown by way of exampleabove, but can be subject to modifications within the framework of thesubsequent patent claims and the inventive concept.

What is claimed is:
 1. A device in a CAN-system, comprising: a number ofmodules (102A, 103A, 104A) assigned to stationary or mobile machinesthat intercommunicate via a digital serial communication connection(107A) using a CAN-system communication protocol; a control means (108A)for realizing a supervisory function over said number of modulesassigned to said stationary or mobile machines, said control meanscommunicating with said number of modules using said CAN-systemcommunication protocol; a plurality of communication means for conveyinginformation by wireless communication between at least two of saidcommunication means, wherein at least one communication means isinterconnected to communicate directly with said control means usingsaid CAN-system communication protocol and at least one communicationmeans is interconnected to communicate directly with said digital serialcommunication connection using said CAN-system communication protocol,said control unit communicating with said modules assigned to stationaryor mobile machines over a unique control frequency to prevent othermachines from being disturbed by one another's frequencies; saidplurality of communication means communicate between themselves with awireless signal protocol that takes no account of the arbitration andconfirmation functions employed by said CAN-system communicationprotocol but otherwise conveys the information content provided by saidinterconnected control means or said digital serial communicationconnection; and said plurality of communication means each have areceiver and a transmitter, wherein each of said receivers executes orassists in converting said wireless signal protocol to said CAN-systemcommunication protocol.
 2. Device according to patent claim 1,characterized in that the modules form a unitary system (201A) when theplurality of communication means intercommunicate and form twoCAN-systems (202A and 205A) which operate separately relative to eachother when the plurality of communication means do not intercommunicate.3. Device according to patent claim 1, characterized in that aparticular pair of communication means intercommunicate with a protocolwhich is distinct from the CAN-protocol.
 4. Device according to patentclaim 1, characterized in that the control means provides information onfaults occurring to a mobile or stationary machine.
 5. Device accordingto claim 1, characterized in that the control means provides informationon faults occurring to a mobile or stationary machine.
 6. Deviceaccording to claim 1, characterized in that the frequencies are chosenwithin the broad-band range of 2.4 GHz or above.